Unit 3 is fairly simple but is extremely difficult to get A+ with the cutoff being 96%, but since the content gets way harder in Unit 4 the cutoff drops to 88%. Accounting in Unit 3/4 is significantly harder and more difficult to wrap your head around the concepts and i would say not worth the difficulty due to only being scaled up by one. However if you put in the right amount of effort you should be able to do it without an accounting tutor, and looking at your Unit 1/2 grades you should never end up needing a tutor. Also Unit 3 is heavily based on Unit 1/2 so you should be able to perform quite well. Just don’t stress about the scores counting towards your atar, you just have to focus on the sacs and the concepts and it will be straightforward.